A1 B1 C1

A2 2 7 1

B2 2 10 3

C2 1 3 1

The table shows the number of students in a class that received letter grades on 2 recent exams. The first exam is shown across the top and is summarized as A1, B1, and C1, and the second exam is in the first column, A2, B2, and C2. Given that a student earns a B on the first exam, what is the probability the student earns a B on the second exam?

A) 25%

B) 33%

C) 50%

D) 67%